DNA Air Filters - Stage 2 Replacement Air Filter for Yamaha P-Y4E14-S2 KitDNA replacement air filters are designed to increase HP and acceleration while providing excellent filtration. These filters are washable and reusable and are custom designed to fit into your existing factory air box. Their drop in design means adding performance is simple. They offer bigger air flow, with almost 99% filtering efficiency. It's ideal for Yamaha YZ 250 450F. This is a replacement filter for customers that have already purchased the DNA